1. Field of the Invention
This invention involves an interactive external defibrillation and drug injection system for use by a human operator for treating cardiac conditions in a patient, particularly in an out-of-hospital or pre-hospital environment. The present invention may also be used within hospitals as well, particularly where intravenous (IV) access has not been established. More specifically, this invention comprises devices capable of measuring and monitoring various physiological indicators in a patient and an expert system capable of analyzing the measured data and making recommendations to an operator for treatment of the patient using any combination of defibrillation, cardioversion, transcutaneous pacing, or intraosseous drug injection. This invention is designed to enable first responders to cardiac emergencies to provide care up to the standard of at least the beginning stages of Advanced Cardiac Life Support (ACLS).
2. Description of the Prior Art
Patients experiencing cardiac emergencies need immediate care. Survival rates for patients experiencing a cardiac emergency improve with early delivery of ACLS care. Defibrillation and the initiation of drug therapies are important components of ACLS. Unfortunately, beneficial drug therapies may be delayed by factors such as delays between the time of arrival of skilled paramedics or other advanced care providers qualified to initiate drug therapies; delays resulting from transportation of a patient to a hospital or other facility where drug therapy may be initiated; and difficulty or failure to establish IV access to a patient experiencing a cardiac emergency.
Treatment of cardiac emergencies may encompass cardiopulmonary resuscitation (CPR), cardioversion, defibrillation, transcutaneous pacing, and/or drug delivery via intraosseous injection. First responders to medical emergencies are frequently not physicians. Such first responders lack the training to make an independent evaluation regarding treatment of the patient with cardioversion, defibrillation, transcutaneous pacing, or drugs. Delays in administering such treatment can result in brain damage or death to the patient.
Prior art defibrillators include microprocessor controlled or "smart" defibrillators comprising algorithms or expert systems capable of receiving and analyzing physiological data from a patient and making a decision or recommendation as to the type of corrective action that should be administered. One type of smart defibrillator is disclosed in U.S. Pat. No. 4,619,265 to Morgan, et al. Morgan discloses an interactive portable smart defibrillator which processes physiological data from the patient and then sends messages or "prompts" to an operator, allowing the human operator to make the final decision regarding the delivery of defibrillation therapy. The device disclosed in Morgan is limited to treatment of the patient with a defibrillator. As explained above, a patient experiencing an emergency cardiac condition often requires drug delivery in addition to defibrillation or cardioversion.
Another type of smart defibrillator is the Heartstart.RTM. 3000, manufactured by Laerdal Medical Corporation of Armonk, N.Y. Use of the Heartstart.RTM. 3000 is contraindicated where the patient is conscious or breathing or where the patient has a pulse or a pacemaker. In general, consciousness, breathing, pulse, and pacemaker are contraindications precluding the use of automatic external defibrillators of the prior art. Patients in need of emergency cardiac care often exhibit one or more of these contraindications.
Another type of smart defibrillator is disclosed in U.S. Pat. No. 5,156,148 to Cohen. The system disclosed in Cohen comprises a central processing unit (CPU) that controls drug delivery devices, cardioverting apparatus, defibrillating apparatus, pacers, and heart assist pumps. However, the system disclosed in Cohen must be attached or implanted into the patient with vascular access devices in place. This presupposes that a cardiac emergency is likely. Such a system would likely be used in intensive care unit or for a very select group of very sick patients. Unfortunately, many, if not most, cardiac emergencies are unexpected and it is unlikely that such system would be in place with pre-existing vascular access for drug delivery.
A system of the type disclosed in Cohen does not require the presence of a physician for its operation, nor does it allow for human intervention in the treatment process. The system disclosed in Cohen is an automatic system where the machine or CPU makes a decision on the treatment to be administered and then administers such treatment without allowing for human input or intervention. The absence of human input or intervention from the operation of the system disclosed in Cohen raises ethical and legal concerns which may limit the application or acceptance of such a system.
There is a critical need for better and more rapid methods of vascular delivery of drugs. The development of new, life saving drugs and better knowledge of how specific drugs work has established that many drugs can prevent death or reduce morbidity if given in a timely manner. Unfortunately, most drugs need to be infused directly into the blood of the general circulation to be effective, and this is not always easily accomplished. Vascular injections and cannulations are procedures requiring professional skills and training that are usually only possessed by doctors, nurses and paramedics. Even these professionals have a significant failure rate and generate time delays for drug delivery in emergency conditions, when veins are often collapsed due to low blood pressure, and several procedures need to be accomplished as soon as possible. Many other professionals and lay personnel, such as flight attendants, police, life guards and teachers, are trained in advanced first aid and CPR, but cannot deliver drugs, due to lack of an effective method that does not require more medical training. Clearly, there is a need for a simple, better and more rapid means of drug delivery to aid both skilled professionals and para-professionals to expand the utility of life saving drugs.
It has long been known that the marrow sinuses of bones are virtual non-collapsible veins. Fluids and drugs have been shown to enter the central circulation after intraosseous (IO) infusions as rapidly or even more rapidly than peripheral vein infusions. This IO method can be used to deliver drugs via the long leg bones, the sternum, or other bones.
Many special needles and devices have been made both to sample marrow and to infuse fluids into the marrow. All of these needles require substantial training and skill for their correct and safe use and take several seconds to minutes to use them properly. Examples of such prior art devices are disclosed in U.S. Pat. Nos. 2,426,535, issued Aug. 26, 1947 to Turkel; 2,773,500, issued Jan. 26, 1955 to Young; 3,750,667, issued Aug. 7, 1973 to Pshenichny et al.; 4,969,870, issued Nov. 13, 1990 to Kramer et al., and in the following articles: Tocantins, L. M. and O'Neill, J. F., "Infusion of Blood and Other Fluids into the General Circulation Via the Bone Marrow," Surg. Gynecol. Obstet., 73, 281-287 (1941); Turkel, H. and Bethell, F. H., "A New and Simple Instrument for Administration of Fluids Through Bone Marrow," War Medicine, 5, 222-225 (1944); Glaeser, P. W. and Losek, J. D. "Intraosseous Needles: New and Improved," 38 Pediat. Emerg. Care. 4, 135-136 (1989); Sacchetti, A. D., Linkenheimer, R., Lieberman, M., Haviland, P., Kryszozak, L. B., "Intraosseous Drug Administration: Successful Resuscitation from Asystole," Pediat. Emerg. Care, 5, 97-98 (1989); Halvorsen, L., Bay, B. K., Perron, P. R., Gunther, R. A., Holcroft, J. W., Blaisdell, F. W., Kramer, G. C., "Evaluation of an Intraosseous Infusion Device for the Resuscitation of Hypovolemic Shock," J. Traum., 30, 652-659 (1990). The above references describe manually inserted needles and techniques which require skill and training for proper use and necessitate many seconds to minutes in use. An automated needle system for delivery of drugs into the marrow would have great utility.
A variety of auto-injection syringes for intramuscular or subcutaneous injections are also known in the art. Examples of such syringes are disclosed in the following U.S. Pat. Nos.: 3,396,726, issued Aug. 13, 1968 to Sarnoff; 3,712,301, issued Jan. 23, 1973 to Sarnoff; 3,882,863, issued May 13, 1975 to Sarnoff et al.; 4,031,893, issued Jun. 28, 1977 to Kaplan et al. However, these syringes are not designed, nor could they be effectively or safely used for injecting into the marrow sinuses of bones, nor do they prevent needles used in the procedures from being exposed so that there is a danger of accidental needle punctures in use of these syringes.
The present invention overcomes the drawbacks of the prior art by providing an interactive external defibrillation and vascular drug injection system comprising an expert system., thereby enabling the system to be operated by a first responder who is not a physician. The expert system of the present invention receives physiological input data from measuring devices attached to the patient, analyzes the data, and issues instructions to the operator regarding patient treatment, including defibrillation, cardioversion, and drug injection.
The present invention may also be used with a patient in need of emergency cardiac care who is conscious, breathing, or who has a pulse or a pacemaker.